Ignition apparatus



.Pf6 j.

' Aug. 23, 1932.

J` L. ARTHUR IGNITION APPARATUS Filed Dec. l1, 1931 lll Patented Aug. 23, 1932 YParr-:T

FrlcE r `JAMES L. ARTHUR, F ANDERSON, INDIANA, ASSIGNOR -T0 DELCO-REMY CORPORA- TION, OF ANDERSON, INDIANA, A CORPRATION 0F DELAWARE IGNITION APPARATUS i Application filed December 1'1, 1931.. Serial No. 580,278.

This invention relates to ignition apparatus for internal combustion engines and more particularly to apparatus for controlling the timing of the ignition in response to pressure in the combustion chamber of the engine.

One form of the apparatus, to which the present invention relates, is disclosed in the copending application of John B. Dyer, Serial No. 580,277 filed Dec. 11, 1931. ln that timer controlling device the spark is maintained in a substantially advanced position and is not substantially retarded .until the combustion pressures have risen to a value such that detonation would likely occur.

lt is an object of the present invention to provide the spark timing controller which operates in response to the explosion pressure and which will operate not only to retard the spark to pevent continued detonationfbut will operate to retard the spark as the throttle isppened from idling position to wide open throttle in order` to increase the speed to the maximum, and will operate to advance the spark as the speed increases when operating the engine at full load Jfrom low to high speed. ln order to accomplish this object l provideu cooperating cylinder and piston members, the former being connected4 with the spark advance lever or plate and the latter being connected by a pipe with an engine cylinder. I provide a relatively light spring which opposes movement of the piston from a position of maximum advance to a position of maximum retard for operation of the engine at explosion pressures below the detonation point. I provide a relatively'stif spring which is ineective to oppose the movement of the piston, but which is engaged by the piston when the' explosion pressure 'nearlyreaches the detonation point, and will yield when detonation occurs to further retard the spark in order to correct the timing `and prevent a recurrence of detonation.

Further objects and advantages of the present invention will be apparent from the ifollowing description, referencebeing had to the accompanying drawing wherein a preferred embodiment of one :form of the present inventionl is clearly shown.

`In the drawing:

Fig. 1 is a diagram showing a form of.

the present invention.

Fig. 2 is a chart illustrating the performance of the present invention. Y

Referring to the drawing, the ignition apparatus comprises a coil- 2O having a primary winding 21 and a secondary winding 22. rlhe primary 21 is connected by a switch 23 with a battery 24 grounded at 25, and is connected by a wire 26 with a terminal 27 of an ignition timer. rlhe terminal 27 is connected by 'a leaf` spring conductor 28 with a circuit breaker lever 29 pivoted at 3() upon a plate 31 which is rotatable about'the axis of a shaft 32 which drives the ignition timer cam 33. 'llie cam 33 cooperates with a rubbing block 34 attached, together with one end of the conductor 28, to the circuit breaker lever 29. Lever 29 carries a contact 35 cooperating with a grounded contact 36. The normal direction of the rotation of the cam 33 is clockwise as indicated by arrow 37. Hence, to advance the spark the circuit breaker lever plate 31 is rotated counterclockwise, and clockwise to retard the spark. A condenser 38 grounded at 39 shunts the contacts as, se.

rlhe `means for controlling the angular relation between the plate 31 and the cam 33 responsive to engine combustion pressure comprises acylinder 40 extending from the engine timer housing 41 and cooperating with a piston 42 connected with a`rod 43 passing through a threaded bushing 44 attached by pin 45 with a link 46 connected by pinv 474 with the plate 31. A spring 48 is interposed between the bushing\44 and piston-42 and isV designed to oppose movement of the piston 42 to retard the spark during operation of the engine at explosion pressures below the detonation pressure. rlhe bushing -44 is adjustable with respect to a bushing 49k which' in turn is adjustable with respect to the housing 41. r Between the bushing .49 and a slidable 'washer 5() there is located a springv 51 of vsuch strength as to prevent movement of the piston toward the right unless it is subject to detonation pressure. The spring 51 is inoperative to vresist ,movement-lof* the piston`42 toward the right to' the position of zero advance; but, when the piston engages the washer 50, this spring 51 resists movement of the piston toward the right until the explosion pressure increases to the detonaf tion point. The cylinder 40 is connected by valve 62 upon its seat.

In the chart shown in Fig. 2 the horizontal axis XZ represents the vehicle speed which may be indicated in miles per hour, and the vertical axis XY is used to represent explosion pressure in the engine cylinder and also degrees of spark advance. The curve AB is the explosion pressure curve under road torque operating conditions. By road torque is meant the torque required to drive a vehicle on a smooth level road from idling speed to maximum speed. As the speed increases, the power which is torque times speed increases. Hence the load increases. It will be seen that as the speed increases the explosion pressure increases from about 30 pounds per square inch, for example, to about `25() pounds per square inch. The curve CB represents the explosion pressure when operating under wide open throttle or full `load operating conditions. At full load and low speed the explosion pressure may attain to 45() pounds per square inch but will decrease to 250 pounds per square inch if the load is removed to permit increase in speed to the maximum speed. Curve DE is the spark advance curve corresponding to curve AB. The spark advance decreases from about 45, for example, to about 20 at full speed. This is desirable because the load is` increasing. Curve FE is the spark advance curve for full load operating conditions and corresponds to curve CB. At full load and low speed, the torque is maximum and the 4explosion pressure may increase nearly to the detonatic point, for example, 450 pounds per square inch. Under these conditions, the piston 42 will move toward the right until it strikes the washer and further movement will be .arrested unless the combustion pressure reaches the detonation point. This position of the piston will give minimum or zero ad- Vance as indicatedby point F. As the load is decreased to permit the speed to increase .with wide open throttle, the pressure decreases as indicated by curve CB :,hence the spark is advanced to as much as 2O degrees for example as indicated by point E. This `advance is desirable since the load is decreasing.

When the engine' is operated with wide open throttle at low speed to develop maximum torque, the explosion pressure may rise to the detonation point. When detonation occurs, the spring 51 which is much stiffer than spring 48 may be overcome and permit the piston to move to retard the spark more than normal or to a retard more nearly approaching dead center position of the engine piston in order to overcome detonation by retarding the spark.

The check valve 62 permits combustion fluid under pressure to be freely admitted to the control cylinder 40, but prevents its too sudden exit by reason of the bleed hole 64. The check valve therefore serves to main.- tain the pressure in cylinder 40 long enough between pressure impulses consequent to `intermittent explosions in the cylinder to effect a correction of the spark timing to avoid a continuance of improper engine operation.

While the form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming.

within the scope of the claims which follow.

What is claimed is as follows: A

1. Ignition apparatus for internal combustion engines comprising, in combination, an ignition circuit interrupter, an engine driven cam for operating the interrupter, and means responsive to explosion pressures in an engine cylinder for controlling the angular relation between the cam and interrupter and comprising a member providing a chamber communicating lwith the engine cylinder, a displacement member in said chamber, a spring continually opposing movement of the displacement member in a direction to retard the timing of the-interrupter, and a spring normally non-operative to oppose retard of timing, but operative when the explosion pressure reaches thedetonation point to retard the timing.

2. Ignition apparatus for internal combustion engines comprising, in combination, an ignition circuit interrupter, an engine driven cam for operating the interrupter, and means responsive to explosion pressure in an engine cylinder for controlling the angular relation between the cam and interrupter and comprising a control cylinder connected tothe engine cylinder, a piston in said control cylinder, a. compressed spring engaging the :piston continually opposing its movement ina direction to retard the timing of the interrupter, a movable stop member engaged by the piston when moved to a positionof normal maximum retard and a spring v nature. i

JAMES L. ARTHUR. 

